The present invention relates in general to an information-bearing laminar assembly suitable for use as an identification card, and more particularly, to an information-bearing laminar assembly having embedded therein a halftone image security feature that is perceptible essentially only in transmitted light.
Many types of personal information-bearing cards and documentsxe2x80x94such as state drivers licenses, voter registration cards, passports, bank cards, credit cards, and certain keycards and so-called xe2x80x9csmart cardsxe2x80x9dxe2x80x94almost invariably include on an information-bearing surface thereof items of information relating to the identity of the card""s authorized holder. Items of personal information commonly included are the authorized holder""s name, address, birth date, signature, and a photographic image of the holder. Although such information can be recorded in encoded machine-readable format (e.g., on a magnetic stripe), almost invariably, at least one item of personal information will be provided either textually or graphically (i.e., as visually-perceptible indicia).
As is well-known, the principal purpose of including personal information on an information-bearing card or document is to both enable and facilitate personal identification. However, as is also well-known, these functions can be undermined if the card or document is easily counterfeited or fraudulently altered.
Thus, in many instances, it is highly desirable that once information is placed onto to the image-bearing surface, the surface be treated in such a manner as to render it difficult or impossible to mechanically alter or amend, at least without rendering it clearly obvious that some tampering with the surface has taken place. To this end, numerous types of laminations have been employed in which the information-bearing surface is heat or solvent-laminated to a transparent surface. The materials for and the process of lamination are selected such that if an attempt is made to uncover the information-bearing surface for amendment thereof, the surface is destroyed, defaced or otherwise rendered apparent the attempted intrusion.
While an identification card that essentially cannot be disassembled without being destroyed may provide suitable resistance against fraudulent alteration, such will not significantly challenge attempts of counterfeiting.
The counterfeiting of identification cards involving as it does the fabrication and issuance of identification cards by persons not authorized to do so presents additional and different security problems to the art. Perhaps the most effective way of preventing counterfeiting would involve strict control over the possession of the materials and equipment involved in the fabrication of the identification card. In most cases, however, this approach would be impractical and most likely impossible. For example, too many of the materials involved are commercially available and used in other applications. Instead, the art""s response to the counterfeiting problem has involved the integration of verification features that are difficult to copy by hand or by machine. The best known of such verification features is the use in the card of a signature of the card""s issuer or bearer. Other verification features have involved, for example, the use watermarks, microprinting, fluorescent materials, fine line details, validation patterns or marking, and polarizing stripes. These verification features are integrated into an identification card in various ways and they may be visible or invisible in the finished card. If invisible, they can be detected by viewing the feature under conditions which render it visible.
All of the verification features discussed above have achieved a measure or success in preventing or discouraging counterfeiting. However, in certain respects, some features are considered to fall short in terms of the idealized performance characteristics desired. In particular, many of the features are expensive and, in the case of features hidden from casual visual inspection, require specialized equipment and trained operator for authentication.
In consideration of the above, a need was felt to include in an information bearing card or document, a novel and unique security feature that would be difficult to reproduce either in a counterfeited document or by the fraudulent alteration of an original, but would for authentication require neither specialized equipment nor trained operators.
In light of the above need, the present invention providesxe2x80x94as its most preferred embodimentxe2x80x94an identification card with an embedded halftone image security feature that is perceptible essentially only by the transmitting light therethrough. The structure of such an identification card can be defined as an information-bearing laminar assembly that comprises an information-bearing inner layer interposed between first and second light-transmissive protective outer layers. The information-bearing inner layer has both visually-perceptible information-bearing indicia on a surface thereof and an imagewise halftone pattern of laser ablated microholes. Each laser-ablated microhole penetrates either completely through the thickness of the inner information-bearing layer or a portion thereof such that the light-transmissivity of the information-bearing inner layer within said half-tone pattern is imagewise differentiated at each microhole.
Central to and in accordance with the invention, the first and second light-transmissive protective outer layers are configured and cover said half-tone pattern of laser-ablated microholes such that, under unassisted visual inspection, the imagewise halftone pattern is (a) substantially imperceptible when the information-bearing laminar assembly is viewed in reflection, and (b) substantially perceptible when the information-bearing laminar assembly is viewed in transmission.
In a product embodiment of the invention, the information-bearing laminar assembly is provided further with destructible peripheral perforations correspondent with the periphery of the information-bearing inner layer. The perforations are configured to fracture if an attempt is made to delaminate the information-bearing laminar assembly, and thus, provides a good positive indicator of a possible occurrence of such security-compromising activity.
In a method embodiment of the invention, there is also described herein a process for manufacturing the inventive information-bearing laminar assembly. The method is characterized by the use of laser ablation technology to provide the assembly""s imagewise halftone pattern of laser-ablated microholes. During ablation, the intensity and duration of the laser irradiation is modulated to imagewise differentiate the penetration depths of said microholes into said polymeric planar material.
In light of the above, it is a principal object of the present invention to provide an information-bearing laminar assembly having embedded therein a halftone image security feature that is perceptible essentially only in transmitted light, wherein the halftone image security feature is an imagewise halftone pattern of laser ablated microholes.
It is another object of the present invention to provide an identification card having an embedded halftone image security feature that can be relatively inexpensive and easy to provide therein, and thus suitable for incorporation into commercial identification card product lines having relatively broad expected user distribution.
It is another object of the invention to provide a method of manufacturing the information-bearing laminar assembly.
It is another object of the present invention to provide means for detecting whether said information-bearing laminar assembly had been delaminated and subsequently relaminated.
It is another object of the present invention to provide an information-bearing laminar assembly, suitable for use as an identification card, that employs a security feature, the authentication of which requires no specialized equipment.
It is another object of the present invention to provide an information-bearing laminar assembly, suitable for use as an identification card, that employs a security feature that is resistant to photocopying or scanning.